Bolster spring unit



May 9, 1939. G. c. CHRISTY ,158,

BOLSTER SPRING UNIT Filed Aug.. 12, 1957 2 Sheets-Sheet 1 222 067722 @xzo/ e 7 12192"! l 5 MM Q8 i wa Patented May 9, 1939 UNITED STATES matte v PArsr iiii'iil BOLSTER SPRING UNIT Application August 12, 1937, Serial No. 153,785

10 Claims.

This invention relates to friction spring units and more particularly to a friction spring unit especially adapted for use with spring assemblies for supporting car truck bolsters.

One of the objects of the invention is the provision of a new and improved bolster supporting spring unit that is provided with novel means for resiliently supporting the load under normal operating conditions and that is provided with mechanism for irictionally resisting abnormal movement of the bolster.

A further object of the invention is the provision of a new and improved bolster spring supporting unit for normally resiliently supporting a railway car bolster together with novel means for preventing harmonic vibration of said unit and of the spring assembly associated therewith.

Another object of the invention is the provision of a new and improved spring unit having friction means associated therewith and provided with means for insuring a prompt release after the friction mechanism has been operated.

A still further object of the invention is the provision of a new and improved spring unit that 1 is simple in construction, easily assembled, comparatively inexpensive to manufacture, efficient in operation and that is not likely to become broken or get out of order. 1 i

Other and further objects and advantages of the invention will appear from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a side elevation of a portion of a railway truck showing the invention in position therein,

' with parts broken away;

Fig. 2 is a vertical section along the line 2-2 '01 Fig. 3;

Fig. 3 is a horizontal section on the line 33 of Fig. 2;

Fig. 4 is a perspective view of the wedge or thrust member;

Fig. 5 is a perspective view of one of the friction shoes; and

Fig. 6 is a perspective view of the shoe engagin spring seat.

In supporting railway cars from their trucks, it is common practice to support the bolster from the side frames of the trucks by spring assemblies at the ends of the bolster. These assemblies comprise a group of conventional spiral springs. These springs oscillate freely unless means be provided for resisting this free movement. This free movement gives proper resiliency and the desired cushioning effect for supporting the car except under conditions that may cause abnormal vibration or under conditions that may develop harmonic action. If permitted to oscillate freely, helical springs are likely to develop harmonic vibration which may be caused by the movement of flat wheels at certain speeds or by the move- 5 ment at certain critical speeds over rail joints or other regular inequalities in the rails or road bed. The harmonic vibration of the springs may increase to such an extent as to cause the springs to go solid, in which event, the trucks or side frames thereof are likely to become distorted or broken. The harmonic action of the springs haseven been known to become so violent as to cause the truck wheels to become derailed. A certain amount of such movement is not objectionable. It is only when the vibration exceeds certain limits that it becomes objectionable.

The present invention seeks to remove these difiiculties by the provision of new and improved means for frictionally resisting such movement after the amplitude of vibration exceeds a certain amount.

It is desirable that the springs have free movement within certain limits for resiliently supporting the car and load. In the form of the device selected to illustrate one embodiment of the invention, the unit is so constructed that it will resiliently support the load under normal operating conditions in such a manner that the car or load has .a free movement and when the vibration of the springs exceeds a certain amount, the shock absorbing mechanism will be automatically brought into operation for not only preventing injury to the railway truck or side frame, but will frictionally resist thefurther downward movement of the bolster.

Referring now to the drawings, the reference character I0 designates a railway truck having a side frame ll provided with a bolster opening l2 through which one end of the bolster I3 extends. The bolster i3 is supported at each end by a spring assembly I 4 which rests on the side frame I l or on a spring board 2|] if the same be used, at its lower end and engages a spring cap beneath the bolster I3 at its upper end for resiliently supporting the 45 bolster. The spring assembly comprises a plurality of helical springs and one or more spring units l6. Since the details of the truck side frame and bolster arrangement constitute no part of the present invention, it is not thought neces- 50 sary to further illustrate or describe the same. 7

Each of the spring units It comprises a casing [1, Fig. 2, having a base or bottom wall l8 and a side wall I!) which, in the form of the construction shown, is cylindrical in cross-seclower, plane, inclined or wedging surface 21.

These wedging surfaces are in planes conver ing inwardly. Any suitable number of friction shoes may be employed, three being shown. These shoes are arranged symmetrically about the inner surface of the casing ll, that is, they are arranged 120 apart.

A spring seat element or wedge member 28 which may, for convenience of description, be termed the lower wedge member, has plane, inclined or wedging faces 29 and is positioned beneath the projections .25 of the shoes and the wedging faces 29 engage the wedging faces 21, respectively, of the shoes, the-re being one wedging face 29 for each shoe. The lower surface of the spring seat element 28 is adapted to be engaged by a, spring 3| seated on the base 18 for resisting the downward movement of the spring seat and shoes, as will presently appear.

The upper wedging faces 26 of the shoes 24 are adapted to be engaged by corresponding Wedge faces or inclined surfaces 32 of a wedge or thrust member 33, which, for convenience of description, may be termed'the upper wedge member, Figs. 2 and 4. The thrust member 33 has a flange 30 at its upper end for reinforcing the same and has a plane wedging surface 32 for each of the wedging surfaces 26 of the shoes, at its lower end. In the form of the construction shown, this thrust member 33 is cylindrical in cross-section although it may be of other forms if desired. The thrust member 33 is provided with an inwardly extending ledge 34 located between its ends and which constitutes an abutment for the upper end of the main spring 35, the lower end of which is seated on the bottom wall or base N3 of the casing ll.

When the parts are assembled, the thrust member 33 extends above the shoes 24 and casing 11 a substantial distance. .Seated on the ledge 34 and extending upwardly above the upper end of the thrust member 33 is a load supporting spring 36, which, together with the hellc'al springs I4, is adapted to support the load under normal operating conditions.

An upper base member 31 having a depressed portion 38 which extends downwardly within the spring 36 and an axial opening in the ledge 34 are provided for the upper end of the unit. This member has a radially extending flange 39 which extends over the upper end of the thrust memher. The spring 36 is of such length and the space between the flange .39 and thrust member 33 as to permit sufficient travel of the flange 39 and bolster without coming in contact with the thrust member, under normal operating conditions.

The depression 38 is provided with an axial opening 4] through which the bolt 23 extends and a nut 42 on the bolt holds the parts in assembled relation and preferably, though not necessarily, under initial compression. 7

In the operation of the device, the movement of the vehicle over inequalities in the road will cause compression of the springs l and the spring 36 and under normal conditions will resiliently support the load. There will, of course, be some movement of the friction shoes and the remaining parts but they will be slight during the normal travel of the car. An' abnormal downward movement of the load will cause the flange 39 to engage the thrust member 33 and this in turn will tend to force the friction shoes 24 downwardly and outwardly into frictional contact with the inner surface of the casing IT. The spring 35 will tend to resist the downward .movement of the thrust member and the spring 3| reacting on the spring seat 28 which in turn, through the wedging faces 29, will resist the downward movement of the shoes 24 and will, at the same time, due to the wedging action of the surfaces 29, tend to force the shoes outwardly into frictional contact with the inner surface of the casing H. The friction between the shoes and the casing will become greater as the shoes are forced downwardly due to the increased resistance of the spring 3| as it is compressed.

This frictional resistance to the downward movement of the thrust member will absorb the energy of the downward movement of the loadand upon release or rebound, the spring 35 will promptly react to release the wedge or thrust member 33 whereby the shoes and other moving parts will promptly move to their normal re leased position.

It is desirable that the expansion of the unit be prompt as otherwise serious damage may result due to the long hammer-like blows that may be delivered to the spring units should they stick or be tardy in expansion. For instance, should the wedging mechanism stick, an abnormal vibration of the bolster would strike the unit and since the same is very firmly set up, i

the wedging mechanism would be almost rigid with the result the bolster would strike it with a long hammer-like blow, whereas, on prompt release,'the space between the flange 39 and thrust member is so small that the shocks due to the flange 31 engaging the thrust member would not be severe. This is considered an important feature of the invention since the load is resiliently supported on free acting springs under normal conditions and is prevented from developing injurious harmonic movement under abnormal conditions.

While the spring unit IE is shown with the thrust member 33 above, it is understood that the unit may be reversed, end for end, if desired.

It is thought from the foregoing taken in connection with the accompanying drawings that the construction and operation of my device will be apparent to those skilled in the art, and that minor changes in size, shape, proportion and details of construction. may be made Without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a railway car, a truck frame having an opening therethrough, a bolster extending into said'opening, a spring assembly Within said opening for supporting one end of said bolster, said assembly comprising a plurality of helical springs and a spring unit, said unit comprising a hollow casing, friction shoes within said casing, yield- 7 ing means for resisting the downward movement .of said shoes, a thrust member, cooperating wedging means on said thrust member and shoes,

spring means acting directly on said shoes and thrust member for resisting compression of the gear and to promptly return the parts to normal position after release, and means carried by said unit for resiliently supporting said bolster and permitting its vertical oscillation without the oscillation of said friction shoes.

2. In a railway car, a truck frame having an opening therethrough, a bolster extending into said opening, a spring assembly within said opening for supporting one end of said bolster, said assembly comprising a plurality of helical springs and a spring unit, said unit comprising a plurality of friction members including a thrust element, resilient means for supporting said bolster from said unit for permitting free vertical movement of said bolster relative to said friction members, and springs for resisting the compression of said unit, one of said springs engaging thrust element for promptly releasing the same after compression of said unit.

3. A bolster spring unit for use in spring assemblies for railway trucks comprising a basemember, a cap member, a plurality of friction elements and wedge members between said base and cap members, a spring for each wedge member for resisting the downward movement thereof, and a spring engaging said upper wedge member and cap member and extending above said upper wedge member.

4. A bolster spring unit for supporting a bolster from a railway truck, comprising upper and lower base members, friction members and wedging elements between said base members adapted to frictionally engage each other when said unit is compressed, springs for resisting the compression of said unit and the relative downward movement of said friction members, each of said wedge elements being independently engaged directly by one of said springs for resisting the compression of said unit.

5. In a spring unit for use in bolster spring assemblies, a tubular base member, a plurality of friction shoes engaging the inner walls of said member, said shoes having plane wedging faces, wedge members having plane wedging faces engaging the wedging faces of said shoes for forcing the latter radially outwardly on the compression of said unit, a spring engaging each wedge for resisting its downward movement, a bolster engaging cap member, and a spring for supporting the same above the adjacent wedge member.

6. In a railway car, a bolster spring unit for use in supporting a railway car bolster, comprising a cylindrical casing, three friction shoes equidistantly spaced for frictionally engaging the interior of said casing, each shoe being provided with a plane wedging surface, a cylindrical thrust member extending into said casing and having three plane wedging surfaces for engaging the wedging surfaces of said shoes, respectively, for forcing the shoes radially outwardly upon the compression of said unit, spring means for resisting the movement of said shoes when the unit is compressed, a spring for engaging said thrust member for releasing the same after compression, and a free acting spring extending above said thrust member for supporting said bolster, said springs being arranged in series.

'7. In a spring unit for use in supporting a railway bolster comprising a casing, friction shoes engaging said casing, means including a thrust member having wedging faces for forcing said shoes outwardly upon the compression of said unit, resilient means including a spring engaging said thrust member for positively releasing the same upon release of said unit, said thrust member having a flange thereon forming a seat for said spring, a spring seated on said flange, an upper base member seated in said spring for normally supporting said bolster above said thrust member, said base member extending radially outwardly over said thrust member for engaging the same for operating said friction elements when said bolster exceeds its normal vibration.

8. In a spring assembly for railway trucks, a hollow base follower, a cap follower member, a plurality of friction shoes frictionally engaging the inner surface of said follower, said shoes having inner and outer wedge faces, each face being a plane surface, a thrust member having a plane wedging surface for each shoe engaging said outer faces, an annular member having a plane wedging face for each shoe and engaging said inner faces, a spring for resisting the inward movement of said thrust member, a spring for resisting the inward movement of said annular member, and a spring for supporting said cap follower above said thrust member.

9. In a railway truck, a side frame having a bolster opening therein, a bolster having one end extending into said opening, a spring assembly for supporting said bolster from said side frame, said assembly comprising a plurality of freely acting springs and a spring unit, said unit comprising a chambered follower, means including wedging and friction mechanism within said follower for frictionally resisting the compression of said unit, and a freely acting spring for assisting in supporting said bolster from said unit and permitting a limited free resilient movement thereof.

10. In a railway car, a bolster spring unit for use in supporting a railway car bolster comprising a. casing, friction elements engaging said casing, a thrust member for forcing said elements into frictional contact with said casing upon the compression of said unit, a plurality of springs for resisting the compression of said unit, one of said springs engaging said thrust member for releasing the same after compression, a freely movable spring reacting on said thrust member, and means supported by said freely movable spring for normally supporting said bolster, said means engaging said thrust member for operating said friction element when said means is abnormally depressed.

GEORGE C. CHRISTY. 

